Have you ever wondered – how much space would need to be covered by solar panels, if we tried to produce the amount of power used by every home in the UK? Well, here’s the answer…

0.3% of the UK. That’s about 827 km². Or, to put it another way, an area about half the size of Greater London.

A Greenpeace video (the one at the top of this page) breaks down what that’d look like if all the solar panels were in the same place. If you’ve watched it and now you’re wondering how we arrived at the final numbers, this blog explains how the calculation was made.

To start with, we worked out how much electricity we’d need to produce. Based on government data from 2015, we know that UK homes consumed about 108.2 billion kWh of electricity over the course of the year.

Next we calculated approximately how much electricity an average solar PV installation produces. To simplify things, we looked at how much power would be produced by south-facing PV panels only. Using data from The Energy Saving Trust, we can say that an average installation (roughly what’s generated by a semi-detached bungalow or a detached house) will produce 3400 kWh over the course of a year.

That means we’d need 31,823,529 of these installations to match all domestic power needs. As an installation of this size will take up about 26 m² (based on the same data from the Energy Saving Trust), we can multiply these figures together to work out that we’d need 827,411,764 m² in total. That’s roughly 827 km².

The UK is about 242,495 km². So we’d need to devote about 0.34% (or 0.3%, if rounded to one decimal place) of total UK land to match the power used by homes in a single year.

If these panels were spread out across the UK, with a particular focus on placing them in sunnier parts of the country in the south and south west, that figure could be even lower too.

Obviously this is very approximate calculation. We focused on south-facing rooftops to make the calculation easier, but in reality solar panels are often installed on southwest, southeast, west and east facing rooftops too.

And in reality, creating a UK power system that runs primarily on renewables wouldn’t just focus on one energy source. Keeping the lights on using clean, sustainable power should involve a big scale up of offshore wind and investment in marine energy as well. A smart, flexible system would include storage, more inter-connectors (that allow power to be transferred throughout Europe) and a mass investment in efficiency. This would not only allow us to integrate variable renewables easily and cheaply, but would – according to research from the National Infrastructure Commission – save consumers billions too.

But the point of the video is this – the potential for solar power is staggering. Even here in our cloudy UK.